Note: Descriptions are shown in the official language in which they were submitted.
3~
l`his invention relates generally to a new and improved apparatus
and method for accu~ulating fuel particles in a portion of a combustion
chamber through the use of a plurality of electrostatic fields.
A method and apparatus utilizing electrostatic fields and corona
discharges to attract fuel particles to a portion of an engine combustion
chamber is disclosed in U.S. Patent No. 4,041,922. The apparatus disclosed
in this patent is utilized to establish a corona discharge at a single
electrode gap which is exposed to the atmosphere in the combustion chamber.
During an engine operating cycle, the atmospheric conditions in the combustion
chamber vary in such a manner that the corona discharge can only be
established during the compression stroke.
Another apparatus for electrostatically attracting fuel particles
to a portion of a combustion chamber is disclosed in U.S. patent No. 4.124,003
issued November 7, 1978 to Michio Abe et al and entitled "Ignition Method
and Apparatus for Internal Combustion Engine". Although this patent dis-
closes several different ignition devices and methods, one of the ignition
devices disclosed in the patent utilizes a main spark plug and a secondary
spark plug. A corona discharge is established at the secondary spark plug
to effect the attraction of fuel particles to a portion of the combustion
chamber adjacent to the main spark plug. The main spark plug effects
initial ignition of the air-fuel mixture. Thereafter the corona discharge
at the secondary spark plug changes to a continuous spark discharge to
positively fire the air-fuel mixture. Still another known device utilizing
a corona discharge in association with a spark plug is disclosed in
U.S. Patent No. 3,974,412.
In addition to the devices set forth above, there are many other
devices for igniting a charge in a combustion chamber. One of these devices
is disclosed in U.S. Patent No. 3,842,819. This device includes a main
electrode having a series gap which is wider than the associated sparking
gap. The purpose oE the relatively wide series gap in the main electrode is
to break down and cause a rapid rise in the voltage at the spark gap. A
somewhat similar ignition device is also disclosed in U.S. Patent No.
-2- ~ b~,
`` 1~1~3~
3,842,818. It should be noted that in both of these patents the series gap
in the main electrode is disposed outside of the combustion chamber and an
electrostatic field at this gap would be ineffective to influence the fuel
particLes in the combustion chamber. In addition, spark plugs having a
plurality of electrode gaps are disclosed in U.S. Patent ~os. 2,071,254;
3,488,556; and 3,577,170.
SUMMARY OF THE PRESENT INVENTION
The present invention relates to a new and improved metnod and
apparatus utilizing strong electrostatic fields and corona discharges to
attract fuel particles to a portion of a combustion chamber. In order to
maximize the accumulation of fuel particles, a plurality of electrostatic
fields and corona discharges are formed at a plurality of electrode gaps
disposed in the combustion chamber.
According to the invention, a method of accumulating fuel particles
in a portion of a combustion chamber comprises the steps of establishing a
first electrostatic field at a first electrode gap located in said portion
of the combustion chamber between a main electrode and a first electrode
surface of a secondary electrode, maintaining the atmosphere in the first
electrode gap separate from the atmosphere in the combustion chamber,
electrostatically attracting fuel particles in the combustion chamber toward
the first electrode gap under the influence of electrostatic forces result-
ing from the first electrostatic field, establishing a second electrostatic
field at a second electrode gap located in said portion of the combustion
chamber between a second electrode surface of the secondary electrode and a
tertiary electrode surface and exposed to the atmosphere in the combustion
chamber, and electrostatically attracting fuel particles in the combustion
chamber toward the second gap under the influence of electrostatic forces
resulting from the first electrostatic field.
According to the invention, there is also provided an apparatus
for use in electrostatically accumulating fuel particles in a portion of a
combustion chamber, said apparatus comprising a first electrode surface area
disposed in said portion of the combustion chamber, a second electrode spaced
--3--
~0~391t~
from and electrically insulated from said first electrode surface area and
disposed in said portion of the combustion chamber, said second electrode
having a first surface area which cooperates with said first electrode sur-
face area to define a first electrode gap, wall means disposed in said portion
of the combustion chamber and enclosing said first electrode surface area
and said first surface area of said second electrode for maintaining the
atmosphere in said first electrode gap separate from the atmosphere in the
combustion chamber, said second electrode having a second surface area
exposed to the atmosphere in the combustion chamber, a third electrode sur-
face area exposed to the atmosphere in the combustion chamber, said third
electrode surface area cooperating with said second surface area of said
second electrode to define a second electrode gap, and means for establish-
ing a first electrostatic field in said portion of the combustion chamber
by establishing an electrical potential across said first electrode gap and
for establishing a second electrostatic field in said portion of the com-
bustion chamber by establishing an electrical potential across said second
electrode gap to electrostatically attract fuel particles to said portion of
the combustion chamber under the influence of said first and second electro-
static fields.
By maintaining the atmosphere in one of the electrode gaps separate
from the atmosphere in the combustion chamber the strength of an electro-
static field established at this electrode gap is maintained substantially
constant as a corona discharge is established at an electrode gap exposed
to the atmosphere in the combustion chamber.
Upon initiation of an engine intake stroke with strong electro-
static fields at both of the electrode gaps, fuel particles are strongly
attracted to a portion of a combustion chamber adjacent to the two electrode
gaps. As the intake stroke continues, the atmospheric pressure in the
combustion chamber is decreased. An initial reduction in the atmospheric
pressure in the combustion chamber enables a corona discharge to begin at
the electrode gap which is exposed to the atmosphere in the combustion
chamber. ~s the combustion chamber pressure continues to decrease, the
":<1,,
~10~39:Lt;
corona discharge turns into a glow discharge.
The occurrence of a corona discharge and a glow discharge at the
electrode gap exposed to the atmosphere in the combustion chamber results
in a reduction in the electrical potential applied across this gap and a
corresponding reduction in the strength of the electrostatic field
surrounding the gap. Of course, a reduction in the strength of the clectro-
static field surrounding the gap exposed to the atmosphere in the combustion
chamber is detrimental to the electrostatic accumulation of fuel particles
in the adjacent portion of the combustion chamber.
In accordance with a feature of this embodiment of the invention,
the strength of the electrostatic field at the
-4a-
10~;1916
enclosed electrode gap is ma~ntained substantially constant
¦during at least a major portion of the intake stroke. This is
Ibecause the atmospheric pressure in the enclosed electrode gap
¦remains constant throughout an operating cycle of the engine.
¦Therefore, a corona discharge and~or glow discharge is not
established due to a reduction in pressure at this electrode
~gap. This means that the electrical potential applied across
the enclosed electrode gap and the strength of the
electrostatic field surrounding the gap will remain
substantially constant as long as the voltage applied to the
electrodes is constant. Since the enclosed electrode gap is
a~so located in the combustion chambe~, the strong
electrostatic field around this electrode gap promotes the
electrostatic accumulation of fuel particles after the
strength of the electrostatic ~ield at the electrode gap
exposed to the atmosphere in the combustion chamber has been
weakened by the establishment of a corona discharge and/or
glow discharge.
In another embodiment of the invention a pair of
electrode gaps are exposed to the atmosphere in the combustion
chamber. In order to maximize the duration of the
electrostatic fields and corona discharges at these electrode
gaps, a secondary electrode which is electrically insulated
from a main electrode and a third electrode surface is
utilized. During the intake stroke of the engine a coxona
discharge is established between the main electrode and the
secondary electrode. Thereafter, a cQrona discharge is
established between the secondary electrode and the third
electrode surface. Establishment of two electrostatic fields
109;~31ti
and corona discharges results in an increase in the duration
and extent of the electrostatic field utilized to attract fuel
particles to a portion of the combustion chamber in which a
lean charge is initially ignited.
Accordingly, it is an object of this invention to provide
a new and improved method and apparatus which are
characterized by the provision of strong electrostatic fields
and/or corona discharges of long duration to enable the ~uel
component in a lean air-fuel mixture to be more effectively
accumulated in a portion of a combustion chamber adjacent to a
spark gap.
Another object of this invention is to provide a new and
improved metbod and apparatus to accumulate fuel particles in
a portion of a combustion chamber and wherein the atmosphere
in an electrode gap is maintained separate from the atmosphere
in the combustion chamber to enable a strong electrostatic
field of relatively long duration to be established at the
electrode gap.
Another object of this invention is to provide a new and
improved method and apparatus to accumulate fuel particles in
a portion of a combustion chamber wherein a secondary
electrode is spaced apart from and electrically insulated from
a main electrode surface and a tertiary electrode surface to
enable a pair of electrostatic fields to be established
between the secondary electrode and the electrode surfaces.
Another object of this invention is to provide a new and
improved method and apparatus as set forth in the two next
preceding objects and wherein corona discharges are provided
in at least some of the electrostatic fields.
-- 1 10~3~16
1~ i
¦i BRIEF DESCRIPTION OF THE DRAWI~GS
I The foregoing and other objects and features of the
IPresent invention will become more apparent upon a
~consideration of the following description taken in connection
~with the accompanying drawings wherein:
Fig. 1 is a fragmentary sectional view of an ignition
plug which is utilized to accumulate fuel particles in a
portîon of a combustion chamber and to subse~uently ignite the
fuel particles;
Fig. 2 is an enlarged view of a portion of Fig. 1
illustrating a pair of electrode gaps which are utiLized in
the establishing of electrostatic fields;
Fig. 3 is a fragmentary sectional view, generally similar
to Fig. 2, of a second embodiment of the invention in which a
secondary electrode is mounted on insulating material used in
association with a main electrode;
Yig. 4 is a fragmenta~y sectional view, generally similar
to Fig. 3, of an embodiment of the invention in which portions
of the secondary electrode are embedded in the body of
insulating material;
Fig. S (on sheet two of the drawings) is a fragmentary
sectional view, generally similar to Fig. 2, of an embodiment
of the invention in which a plurality of electrode gaps are
formed in association with a secondary electrode which is
electrically insulated from and mounted on a housing of an
ignition plug;
Fig. 6 is a fragmentary sectional view, generally similar
to Fig. 5, of an embodiment of the invention in which the
secondary electrode is mounted on a body of insulating
material su~rounding a main electrode;
109;~916
; Fig. 7 (on sheet three of the drawings) is a fragmentary
slectional view of another embodiment o~ the invention which is
generally similar to the embodiment of the invention shown in
E~i9o 6;
Fig. 8 is a fragmentary sectional view of another
embodiment of the invention which is generally similar to the
embodiment of the invention illustrated in Fig. 5;
Fig. 9 (on sheet two of the drawings) is a fragmentary
sectional view illustrating the manner in which an ignition
plug constructed in accordance with the present invention is
utilized in association with an auxiliary combustion chamber;
and
Fig. 10 (on sheet three of the drawings~ is a fragmentary
sectional view, generally similar to Fig. 9, illustrating an
embodiment of the invention in which a portion of the
auxiliary combustion chamber is defined by one of the
electrodes of the ignition plug.
DESCRIPTION OF SPECIFIC PREFERRED
EMBODIMENTS OF THE INVENTION
An ignition plug 20 constructed in accordance with the
present invention is shown in Fig. 1 mounted on a cylinder
head 22 of a four-cycle internal combustion engine. The
ignition plug 20 has a metal housing 24 with external threads
26 which engage internal threads 28 formed in the cylinder
head 22 to hold the plug. A high voltage generating device 32
is connected with a generally cylindrical main or central
electrode 34 of the ignition plug 20.
,
~ 1093916
1, 1
¦ The high voltage generating device 32 is connected with a
suitable battery (not shown) and includes an oscillating,
~oltage-raising transformer which is effective to raise the
~negative voltage o~ a battery. This negative polarity voltage
is impressed on the central electrode 34 through a voltage
rectifier~ During at least the intake and compression strokes
of the engine, a constant negative voltage of approximately
eight thousand volts is applied to the main electrode 34 by
the voltage source 32. At the end of the compression stroke,
the nega~ive voltage applied to the main electrode 34 is
increased to approximately twenty-five thousand volts.
~lthough the voltage source 32 could have many different known
~onstruCtions, it is contemplated that the voltage source
could advantageously be constructed in the manner disclosed in
U.S. Patent No. 4,041,922. It is also contemplated that a
~ource of positive polarity voltage could be utilized if
~esired.
The ignition device 20 includes a cylindrical secondary
electrode 38 (see Fig. 2) which Cooperates with the main
electrode 34 and a third or tertiary electrode 40 to form a
pair of electrode gaps 42 and 44 Which are disposed in the
engine combustion chamber 60. The first electrode gap 42 is
~ormed between a circular end face 48 Of the cylindrical main
electrode 34 and a circular end face 50 of the cylindrical
secondary electrode 38. The second electrode gap 44 is formed
~etween a circular outer end face 54 of the secondary
el~ctrode 38 and a generally rectangular tertiary electrode
~urface 56 on the tertiary electrode 40. The tertiary
lectrode 40 is integrally formed With a metallic housing 24
,
lQ'~;391
li
and is mechanically and electrically connected with the
cylinder head 22.
In accordance with a feature of the present invention,
the atmosphere in the electrode gap 42 is maintained separate
from the atmosphere in the engine combustion chamber 60. This
is accomplished by surrounding the electrode gap 42 with a
body 76 of ceramic insulating material which electrically
insulates the main and secondary electrodes 34 and 38 from the
housing 24. Since the atmosphere in the electrode gap 42 is
maintained separate from the atmosphere in the combustion
chamber, the characteristics of the atmosphere in the
electrode gap 42 remain constant during operation of the
engine. Of course, the characteristics of the atmosphere in
the combustion chamber 60 and the electrode gap 44 vary during
the operation of the engine.
Since the pressure and composition in the atmosphere at
the electrode gap 44 varies during the operation of the
engine, the electrical conductivity of the atmosphere in this
electrode gap also varies. However, the pressure and
composition of the atmosphere in the electrode gap 42 is
maintained constant during operation of the engine.
Therefore, the electrical conductivity characteristics of the
atmosphere in the electrode gap 42 remain constant during
operation of the engine.
To promote the electrostatic attraction of fuel particles
to the portion of the combustion chamber 60 adjacent to the
ignition plug 20 during operation of the engine, electrostatic
fields are established in the combustion chamber at the
electrode gaps 42 and 44. This is accomplished by the
~Q~91~i
impression of the relatively large negative polarity voltages
lon the central electrode 34 by the voltage generating device
32. Thus, during operation o~ the engine, the voltage
generating device 32 is effective to constantly apply a
relatively laege negative voltage of approxi~ately eight
thousand volts to the main electrode 34. It should be
understood that a positive polarity voltage may be utilized if
desired.
The electrode gap 42 is of a relatively small si~e,
preferably within the range of 0.2 to 0.8 mm. Therefore the
secondary electrode 38 is charged across the gap 42 to the
same voltage as the main electrode 34. This relatively large
voltage results in a strong electrostatic field being
established between the outer end surface 48 of the main
electrode 34 and the inner end surface 50 of the secondary
electrode 38. This electrostatic field extends into the
combustion chamber 60 in the vicinity of the electrode gap 42.
A second electrostatic field is established in the
combustion chamber 60 tFig. 1) between the outer end surface
54 (Fig. 2) of the secondary electrode 38 and the tertiary or
housing electrode 40. Depending upon the pressure and
co~position of the atmosphere in the combustion cha~ber 60,
the electrostatic field between the secondary electrode 38 and
the tertiary electrode 40 continuously fluctuates through a
corona or glow discharge at the electrode gap 44. However at
the end of the compression stroke, the voltage generating
device 32 is effective to apply an increased negative voltage
to the main electrode 34 to cause sparking to occur at the
electrode gap 44.
10~3~L6
Whan the p~essure in the combustion chamber 60 is reduced
during an initial portion of an intake stroke, the voltage
potential between the secondary electrode 38 and the tertiary
electrode 40 is effective to establish a corona discharge
across the gap 44. This results in a reduction in the
electrical potential across the gap 44 with a resulting
decrease in the strength of the electrostatic field eminating
from the gap 44. As the intake stroke continues, the pressure
in the co~bustion chamber is further reduced and the corona
discharge changes to a glow discharge. As this occurs, the
strength of the electrostatic field is further reduced.
The pressure and composition of the atmosphere in the
electrode gap 42 remains constant during operation of the
engine so that a substantially constant electrical potential
is established across the gap 42 during the intakP stroke.
This results in a relatively strong electrostatic field of
substantially constant strength being formed in the combustion
chamber 60 adjacent the electrode gap 42. It should be noted
that the electrical potential across the electrode gap 42 is
not sufficient to establish either a corona discharge or a
glow discharge at this electrode gap during operation of the
engine.
During the intake stroke, the strong electroseatic field
extending from the electrode gap 42 is effective to negatively
ionize fuel particles in a relatively lean air-fuel mixture
which is being introduced into the combustion chamber 60. The
resultinq electrostatic forces on the air-fuel mixture results
in a flow of the air fuel mixture through generally circular
side openings 64 formed in the housing 24 toward the main
9 16
¦e:Lectrode 34, that is in the dieection of the arrows in Fig.
2. At this time, the fuel particles are atomized under the
influence of the strong negative D.C. voltage of approximately
eight thousand volts which is being applied to the main
electrode 34. The negatively charged fuel particles are
¦attracted to a generally cylindrical inner surface 6~ (Fig. 2)
of the housing 24 which is at ground potential. In addition,
! the neqatively charged fuel particles accumulate on the
tertiary electrode 40 which is also at ground potential.
¦ The housing 24 has a generally circular open end 72
through which the extremely lean air-fuel mixture flows after
uel particles have been electrostatically accumulated on the
inside of the housing. During the intake stroke, the
atmospheric pressure in the combustion chamber 60 is reduced
so that a corona discharge can be established at the electrode
gap 44 between the tertiary electrode 40 and the secondary
electrode 38. However, the establishment of the corona
discharge at the electrode gap 42 is effective to reduce the
electrostatic precipitation of fuel particles in the
combustion chamber 60 adjacent to the ignition plug 20.
As the engine operating cycle continues and the
compression stroke begins, the pressure in the combustion
chamber 60 increases as the relatively lean air-fuel mixture
in the combustion chamber is compressed. As this occurs, the
conditions for establishing a corona discharge across the
electrode gap 44 become less favorable. Thus, sometime after
the compression stroke has been undertaken and before ignition
of the air-fuel mixture in the combustion chamber 60, a corona
discharge is discontinued between the circular end face 54 of
10:.~391~i
¦the secondary electrode 38 and the surface 56 of the tertiary
¦electrode 40. This results in the simultaneous establishment
¦of stronq electrostatic fields at the electrode gap 42 and at
the electrode gap 44.
The simultaneous establishment of a pair of electrostatic
fields at the electrode gaps 42 and 44 promotes the
accumulation of fuel particles in the combustion chamber ~0
adjacent to the ignition plug 20. This is because the first
electrostatic field at the electrode gap 42 causes the
air-fuel mixture to flow radially inwardly through the side
openings 64 in the manner previously explained. This flow of
the air-fuel mixture is directed toward the second electrode
gap 44. The electrostatic field at the second electrode gap
44 further ionizes the fuel particles to promote the
electrostatic accumulation of the negatively charged fuel
particles on the housing 24 adjacent to the tertiary electrode
40. Thus, the effect of the two electrostatic fields at the
electrode gaps 42 and 44 is additive to further enhance the
electrostatic accumulation of fuel particles adjacent to the
ignition plug 10.
At the end of the compression stroke, the magnitude of
the negative voltage impressed on the central electrode 34 by
the voltage generating device 32 is substantially increased to
approximately twenty five thousand volts. This causes a spark
to extend across the electrode gap 44 between the end face 54
of the secondary electrode 38 and the surface 56 of the
tertiary electrode 40. This spark ignites the fuel particles .,
which have been electrostatically accumulated around the
ignition plug 20. By electrostatically accumulating fuel
''s~''` ,,,`~
1093916
particles adjacent to the tertiary electrode 40~ a relatively
rich air-fuel mixture is provided around the ignition plug 20
even though the total charge introduced into a cylinder of the
engine is very lean. This enables an air-fuel mixture which
is leaner than could normally be ignited to be burned in an
engine with a resulting reduction in the pollutants generated
by the engine as described in United States Patent No. 4,041,922
and in the aforementioned United States patent No. 4,124,003.
In accordance with an important feature of the present
invention, the effective duration of the electrostatic fields
associated with the ignition plug 20 is increased in order to
increase the number of fuel particles which are
electrostatically accumulated adjacent to the ignition plug
20. In the embodiment of the invention illustrated in Figures
1 and 2 the increased duration of the electrostatic field is
obtained by enclosing the electrode gap 42 with the generally
cylindrical body 76 of insulating material. The insulating
material 76 extends upwardly into the metallic body 24 of the
ignition plug 20 and is effective to insulate the main
electrode 34 from the metallic body 24 of the ignition plug.
The body 76 of electrically insulating material has a
cylindrical outer surface 80 of a smaller diameter than the
cylindrical inner surface 68 of the metallic plug housing.
This results in the formation of an annular space 82 between
the cylindrical inner surface of the plug housing 24 and the
body 76 of the electrically insulating material to accommodate
the flow of the air-fuel mixture from the side openings 64 to
the open end 72 of the ignition plug housing 24.
`
l(J5t;~9i6
In the embodiment of the invention i~lust~ated in Fi~s.
and 2, the cylindrical secondary electrode 38 is held in the
body 76 of insulating material by frictional forces between a
cylindrical outer surface o~ the electrode and a cylindrical
inner surface of the body 76 of insulating material. In the
embodiment of the invention illustrated in Figs. 3 and 4,
mounting prongs or legs are used in association with the
secondary electrode to further hold it against axial movement
relative to a body of insulating material. Since the
embodi~nents o~ the ir~vention il~ ust~ated in Fi~s . 3 and 4 a~e
generally similar to the embodiment of the invention
illustrated in Figs. 1 and 2, similar numerals will be
ùtilized to designate similar components, the suffix letter
"a" being associated with the numerals of Fig. 3 and the
suffix letter "b" being associate~ with the numerals of Fig. 4
to avoid confusion.
In the embodiment of the invention illustrated in ~ig. 3,
the ignition plug 20a has a metallic housing 24a with circular
openings 64a through which flow of a relatively lean air-fuel
mixture is electrostatically induced in the manner previously
explained. The ignition plug 20a has a main or central
electrode 34a which is enclosed by a body 76a of electrically
insulating material~ A secondary or floating electrode 38a is
connected with the body 76a of electrically insulating
material by a pair of legs or prongs 90 and 92. The mounting
legs 90 and 92 are embedded in the body 76a of electrically
insulating material to acc~lrately position an inner surface
50a of the secondary electrode 38a relative to an end surface
48a of the main electrode 34a to form an electrode gap 42a~
iO~3916
The atmosphere in the electrode gap 42a is maintained separate
from the atmosphere in the associated combustion chamber to
enable a strong electrostatic field to be established across
the electrode gap 42a at any desired time in an operating
cycle of an engine.
A second electrode gap 44a is formed between the
secondary electrode 38a and a tertiary or housing electrod~
40a. The electrode gap 44a is exposed to the atmosphere in
the combustion chamber so that a corona discharge is
established across the gap 44a in the manner previously
explained in connection with Figs~ 1 and 2. When the charge
in the combustion chamber is to he ignited, a spark is
established across the gap 44a.
In the embodiment of the invention illustrated in Fig. 4
the secondary electrode 38b is provided with a pair of legs
90b and 92b which are embedded in the body 76b of electrically
insulating material. This results in the formation of a first
electrode gap 42b between the secondary electrode 38b and a
main electrode 34b. A second electrode gap 44b is formed
between the secondary electrode 38b and a tertiary electrode
40b. The atmosphere in the electrode gap 42b is maintained
separate from the atmosphere in the associated combustion
chamber to enable a strong electrostatic field to be
established across the electrode gap 42b while a corona
discharge is established across the electrode gap 44b. This
enables the duration of the electrostatic field to be
increased to increase the electrostatic accumulation of fuel
particles during each operating cycle of an engine.
91~
¦l In the embodiments of the invention illustrated in Figs.
1 through 4, the duration of the electrostatic field in the
combustion chamber of an engine is increased. This is
accornplished by establishing an electrostatic field across an
electrode gap having an atmosphere which is separa~e from the
atmosphere of the combustion chamber while a corona discharge
is being established in the combustion chamber. In the ¦-
embodiment of the invention illustrated in Fig. S a pair of
electrode gaps are both exposed to the atmosphere in the
combustion chamber. In accordance with a feature of this
embodiment of the invention, the duration and pattern of the
electrostatic field is enhanced by an ungrounded secondary
electrode which holds the applied voltage to promote the
accumulation of fuel particles adjacent to the ignition plug.
The ignition plug 130 of Fig. 5 has a metal housing 132
which i5 connected with a cylinder head 134 of an engine by
external thread convolution 136 formed in the housing.
Although only a relatively small portion of the housing 132
has been shown in Fig. 5, it should be understood that it has
the same general configuration as the housing 24 of Fi9 . 1.
The ignition plug 30 has a central or main electrode 140
which is connected with a voltage generating device (not
shown) of the same construction of the voltage generating
device 32 of Fig. 1. This voltage generating device is
effective to apply a negative voltage of approximately eight
thousand volts to the central ele~trode 140. The central
electrode 140 is electrically insulated frorn the housing 132
and the cylinder head 134 by a body 142 of electrically
insulating material. The insulating material 142 is effective
~0~;19i6
to fixe ly mount tbe central electrode 140 in the housing 132
¦in a well known manner.
A generally cylindrical secondary electrode 148 is
mounted on an axially outer end portion 152 of the housing 132
by an annular body 154 of insulating material. The secondary
electrode 148 is coaxial with the main electrode 140 and
circumscribes the end portion of the main electrode. The
insulating material 154 is effective to insulate the secondary
electrode 148 from the housing 132. A tertiary or third
electrode is formed by the housing 132. In the embodiment of
the invention illustrated in Fig. 5, the tertiary of the
housing electrode is provided with an inwardly projecting
electrode arm 158. The electrode arm 158 extends through an
opening 160 in the sidewall of the secondary electeode 148.
During operation of an engine in which the ignition plug
130 is used, a negative voltaqe of approximately eight
thousand volts is impressed on the center electrode 140. This
voltage is effective to establish an electrostatic field
between a conical end portion 162 of the central electrode 140
and an inner surface 164 of the secondary electrode 148.
second electrostatic field is then established between the
3enerally cylindrical outer surface 168 of the secondary
~lectrode 148 and the tertiary electrode formed by the housing
132 and the inner surface of the cylinder head 134 which are
at the same electrical potential. Of course as the intake
stroke continues and the atmospheric pressure in the
combustion chamber is decreased, a first corona discharge is
,established between the electrode 140 and the secondary
electrode 148. Immediately thereafter, a second corona
~0~39i~
¦ discharge is established between the secondary electrode 148
I and the tertiary electrode formed by the housing 134. It
should be noted that the housing 132 and cylinder head 134
cooperate to provide an annular electrode surface which
circumscribes the cylindrical secondary electrode 148 and is
coaxial with the secondary electrode.
The electrostatic field across the electrode gap between
the secondary electrode 148 and the tertiary electrode formed
by the housing 132 and cylinder head 134 ionizes the fuel
particles. The resulting negatively charged fuel particles
are attracted to the portion of the combustion chamber around
the ignition plug 130. The effect of the electrostatic field
between the secondary and tertiary electrode 148 and 134
causes the air-fuel mixture to flow radially inwardly through
side openings 172, 174 and 160 formed in the secondary
electrode. This flow is directed through an annular second
electrode gap formed between the conical end portion 162, the
main electrode 140 and the circular inner surface 164 of the
secondary electrode 148. The air-fuel mixture then flows out
of the secondary electrode 148 through a circular outlet
opening formed by the throat of a converging-diverging nozzle
surface 180.
As the air-fuel mixture passes through the annular
electrode gap between the end portion 162 of the main
electrode 140 and the inner surface 164 of the secondary
electrode, the fuel particles are further ionized by the
electrostatic field. During the operating cycle of the
engine, the magnitude of the negative voltage applied to the
central electrode 140 is increased to approximately twenty
10S~91
,
¦five thousand volts. This causes a spark to form in a gap 184
between an end surface of the arm 158 of the ~ertiary
electrode and the side of the main electrode 140. This spark
is effective to i~nite the fuel particles which have been
electrostatically attracted to the area around the ignition
plug 130.
By having the secondary electrode 148 electrically
insulated from the housing 132 and cylinder head 134, two
electrostatic fields are established. The secondary electrode
~148, which is not grounded, is effective to hold the applied
voltage to increa~e the extent of the electrostatic fields.
If the secondary electrode 148-was not electrically insulated
from the housing 132 and cylinder head 134, it would be
impossible to establish an electrostatic field between the
outside of the secondary electrode and the housing 132 and
cylinder head 134. By establishing two electrostatic field
areas, that is on both the inside and outside of the secondary
electrode 148, the extent of the pattern of the electrostatic
fields is increased to increase the extent to which the fuel
particles are ionized. In addition, by having the secondary
electrode 148 electrically insulated from the housing 132, the
duration of the electrostatic fields is increased.
The embodiment of the invention shown in Fig~ 6 is
generally similar to the embodiment of the invention shown in
¦Fig~ 5. However, in the embodiment of the invention shown in
Fig. 6 the secondary electrode is mounted on a body of
material which electrically insulates the main electrode from
the housing. This eliminates need for additional body 154 of
material to electrically insulate the secondary electrode from
10~;i91$j 1
the housing. Since the emùodiment of the invention
i.Llustrated in Fi~. 6 is generally similar to the embodiment
c,f the invention illustrated in Fig. 5, similar numerals will
be utilized to designate similar components, the suEfix letter
"c" being associated with the embodiment shown in Fig. 6 in
order to avoid confusion.
The ignition device 130c of Fig. 6 has a metal housing
132c which is connected with the cylinder head of an engine in
the same manner as is the ignition device 130 of Fig. 5. The
ignition device 130c has a central or main electrode 140c
which is enclosed by a body 142c of electrically insulatin~
material. A metal secondary electrode 148c is connected with
the body of electrically.insulating material 142c by an
annular mounting flange 188 which is embedded in the
electrically insulating material 142c. This results in the
secondary electrode 148c being electrically insulated f.rom the
metal housing 132c, the engine cylinder head, and the main
electrode 140c.
During operation of an engine with the ignition plug
130c, a relatively large negative voltage of approximately
eight thousand volts is appl~ed to the main electrode 140c.
This results in an electrostatic field bein~ established
between a conical end portion 162c of the electrode 140c and
the circular inner surface 176c of the secondary electrode
148c. In addition, an electrostatic field is established
between the outer side surface 168c of the secondary electrode
148c and the housing 132c and an associated cylinder head.
The secondary electrode 148c functions to extend the pattern
of electrostatic field in the manner previously explained in
connection with the secondary electrode 148 of Fig. 5.
iO~9i~i
I
Although the embodiments of the invention shown in Figs~
S and 6 have housings with inwardly projecting arms 158 and
158c which form spark gaps adjacent to the main electrodes 140
and 140c, it is contemplated that the electrode arms could be
eliminated if desired. This has been done in the embodiments
of the invention illustrated in Figs. 7 and 8. Since the
embodiments of the invention illustrated in Figs. 7 and 8 have
many components which are similar to the compon~nts in the
embodiments of the invention illustra~ed in Figs. 5 and 6,
similar numerals will be utilized to designate similar
components, the suffix letter "d" being associated with the
numerals used in association with the embodiment of Fig. 7 and
the suffix letter "e" being used with the numerals associated
with the embodiment of the invention illustrated in Fig. 8 to
avoid confusion.
The ignition device 130d of Fig. 7 has a metallic housing
132d which is connected with the cylinder head of an engine.
A relatively large negative voltage of approximately eight
thousand volts is applied to a central electrode 140d~ The
central electrode 140d is electrically insulated from the
housing 132d by a body 142d of ceramic material. A generally
cylindrical metal secondary electrode 148d is mounted on the
body of electrically insulating material 142d by an annular
mounting section 188d. The cylindrical metal secondary
electrode 148d circumscribes and is disposed in a coaxial
relationship with the main electrode 140d.
During an operating cycle of an engine, the relatively
large negative voltage applied to the main electrode 140d
results in establishing an electrostatic field between a
iO~3;~9i~i
l¦cylindrical outer end portion 162d oE the main electrode and a
I cylindrical inner surface 176d of the secondary electrode
148d. A second electrostatic field is established across the
gap between the circular ou~er surface of the housing 132d and
the cylindrical outer surface 168d of the secondary electrode
148d. The electrostatic field formed between the central
electrode 140d and the secondary electrode 148d and the
electrostatic field between the secondary electrode 148d and
Ithe housing 132d are effective to ionize the fuel particles to
¦electrostatically accumulate them adjacent to the ignition
plug 130d i~ the manner previously explaine~. Of course when
the pressure in the combustion chamber is reduced to a
sufficient extent, corona discharges are established in the
electrostatic fields.
At a predetermined time during the operating cycle of the
engine, a negative voltage of approximately twenty five
thousand volts is applied to the central electrode 140d. This
results in the formation of a spark between the central
electrode 140d and the inner surface 176d of the secondary
electrode 148d. In addition, a second spark is formed between
the outer surface 168d of the secondary electrode 148d and the
housing 132d.
In the embodiment o~ the invention illustrated in Fig. 8,
a cylindrical metal secondary electrode 14~e is mounted on the
housing 132e of an ignition plug 130e by an annular body 154e
of electrically insulating material. During operation of an
engine, a negative voltage of approximately eight thousand
volts is applied to a main electrode 140e. The main electrode
140e is electrically insulated from the housing 130e by a body
142e of electrically insulating material. The relatively
~ 3~3i~ 1
Large negative voltage results in the establishment of a
strong electrostatic field between the outer end portion 162e
of the central electrode 140e and the cylindrical inner
surface 176e of the secondary electrode 148e. In addition, an
electrostatic field is established between the cylindrical
outer surface 168e o~ the secondary electrode 148e and the
housing 132e.
When the fuel particles which have been ~lectrostatically
accumulated adiacent to the ignition plug 130e are to be
ignited, a relatively large negative voltage of approximately
twenty five thousand volts is applied to the central electrode
140e. This results in the establish~ent of a spark between
the central electrode 140e and the secondary electrode 148e
and in the establishment of a spark between the secondary
electrode 148e and the housing 132e.
In the embodiment of the invention illustrated in Figs. 1
through 8, the various ignition plugs have been described as
being mounted directly on the cylinder head of an engine with
the inner end portions of the ignition plugs exposed to a
combustion chamber formed between the cylinder head, piston
and cylinder wall of an engine. However, it is contemplated
that it may be desirable to utilize these ignition devices in
association with auxiliary combustion chambers similar to the
ones disclosed in U.S. Patent No. 4,041,922 and in U.S. patent
application Serial No. 732,971 filed October 15, 1976. Such
an arrangement is disclosed in the embodiment of the invention
illustrated in Fig. 9.
In the embodiment of the invention illustrated in Fig. 9,
an ignition plug 200 is mounted in an adapter 202. The
adapter 202 is connected with a cylinder head 204 of an
.. ... .. .
1051391~L;
lengine. The engine has a piston 208 which cooperates with a
¦cy~inder waLl 210 and the cylinder head 204 to form a main
combustion chamber 212. A relatively lean air-fuel mixtuee is
introduced into the combustion chamber 212 through an intake
valve 214 dur ing an intake stroke of the engine.
In accordance with a feature of this embodiment of the
invention, an auxiliary combustion chamber 216 is formed by a
generally hemispherical housing 218. An annular secondary
electrode 222 is mounted in the housing by engagement of ~n
annular flange 223 with an annular body 224 of electrically
insulating material. The Ceramic insulating material 224
electrically insulates the secondary electrode 222 from the
housing 218 and cylinder head 204~
During operation of the engine, a voltage source 228 is
effective to apply a relatively large negative voltage of
between approximately eight thousand volt5 to a central
electrode 23~ of the ignition device 220. This results in the
establishment of a strong electrostatic field between a
conical end portion of the central or main electrode 232 and
the secondary electrode 222. Since the secondary electrode
222 is electrically insulated from the metal hou5ing 218, an
electrostatic field will also be established between the
secondary electrode 222 and the housing 218 whiCh forms the
uxiliary combustion chamber.
The electrostatic field established between the main
lelectrode 232 and the secondary electrode 222 and the
electrostatic field established between the secondary
~lectrode 222 and the auxiliary chamber housing 218 are
effective to ionize the fuel particles in a relatively lean
!
¦air_fuel mixture. This results in the electrostatic
¦ac:cumulation of negatively charged fuel particles in the
auxiliary combustion chamber 216. A plurality of openings or
apertures 236 are formed in a radially extending flange 223
which connects the secondary electrode 2~2 with the body 224
of insulating mateeial.
During operation of the engine, electrostatic fields
between the main electrode 232 and the secondary electrode 222
and the housing chamber 218 induces a flow of lean air-fuel
mixture from the combustion chamber 212 through a circular
opening 244 into the auxiliary combustion chamber 215. The
electrostatic field between the secondary electrode and the
housing chamber 218 causes the air-fuel mixture to flow toward
the central electrode 232 through a circular opening 246 in
the annular secondary electrode 222. As the air-fuel mixture
passes through the annular secondary electrode, it is further
ionized under the influence of the electrostatic field between
the main electrode 232 and the secondary electrode 222. When
the pressure in the combustion chamber 212 is sufficiently
reduced, corona discharges are established between the
electrodes 232 and 222 and between the electrode 222 and
housing 218.
The negatively charged fuel particles are deposited in
the area of a sparking electrode 250. An extremely lean
outward flow of an air-fuel mixture from which fuel particles
have been deposited is promoted through the openings 223 in
the annular flange 240. This outward flow of very lean
air-fuel mixture passes through the opening 244 into the
combustion chamber 212.
~7
At a suitable time during the operating cycle of the
engine, the negative voltage impressed on the ma;n electrode
232 by the voltage source 228 is increased to approximately
twenty five thousand volts. This results in formation of a
spark between the electrode 250 and the main electrode 232.
Since fuel particles have been electrostatically accumulated
around ~he sparking electrode 250, the spark ignites the
air-fuel mixture in the auxiliary combustion chamber 216. The
resulting flame in the auxiliary combustion chamber is
directed ouwardly through the opening 244 into the main
combustion chamber 212. This flame is effective to ignite the
lean air-fuel mixture in the main combustion chamber.
In the embodiment of the invention illustrated in Figure
9, the auxiliary combustion chamber 216 is formed by the use
of a separate shell or housing member 218 in the manner similar
to that described in United States Patent No. 4,041,922 and the
aforementioned United States patent No. 4,124,003 issued
November 7, 1978. In the embodiment of the invention illustrat-
ed in Figure 10, the housing shell 218 is eliminated and the
auxiliary combustion chamber is formed by the secondary electrode.
Thus, the functions of the secondary electrode 222 and the auxi-
liary chamber shell 218 of the embodiment of the invention
illustrated in Figure 9 are combined into a single element in
the embodiment of the invention illustrated in Figure 10. Since
the embodiment of the invention illustrated in Figure 10 has
many elements which are similar to the elements of the embodiment
of the invention illustrated in Figure 9, similar numerals will
be utilized to designate similar components, the suffix letter
"f" being associated with the numerals of Figure 10 to avoid
confusion.
- 28 -
`I 10~;~9~
~''
An ignition plug 200f is connected ~7ith cylinder head
~204f of an engine by a suitable mounting adapter 202f. The
~ignition plug 200f has a main electrode 232f which i5
¦connected with a voltage generating device 228f. An auxiliary
¦combustion chamber 216f is defined by a generally
hemispherical secondary electrode 222f which is mounted on the
cylinder head 204f by an annular body 224f of electrically
insulating material.
During operation of the engine, the voltage generating
device 228f is effective to apply a relatively high negative
voltage of approximately eight thousand volts to the main
'electrode 232f. This results in the establishment of a strong
electrostatic field between the center electrode 232f and the
secondary electrode 222f. In addition, an electrostatic field
is established between the secondary electrode 222f and the
Fylinder head 204f.
The combined influence of these electrostatic fields
results in lean air-fuel mixture being electrostatically
~ttra~ted to the auxiliary combustion chamber 216f. As the
~ir-fuel mixture is ionized by thP electrostatic fie-ds, the
negatively charged fuel particles are deposited in the area of
sparking electrode 250f. An extremely lean air-fuel mixture
from which fuel particles have been electrostatically
eposited then leaves the auxiliary combustion- chamber 216f
~hrough the circular opening 244f through which the air-fuel
~ixture initially entered the auxiliary combustion chamber.
~t the end of the compression stroke, the voltage source 228f
s effective to impress a negative voltage of a relatively
large magnitude on the main electrode 232f to cause a spark
10S~3916
beeween the =ain electrode and the sparking electrode 250f.
This spark is effective to ignite the fuel particles which
were electrostatically deposited in the area of the sparking
electrode,
In view of the foregoing description, it is apparent that
the present invention provides a new and improved method and
apparatus of using electrostatic fields and corona discharges
to attract fuel particles to a portion of a combustion
chamber. In order to maximize the effect of the electrostatic
fields during each operating cycle, a plurality of
electrostatic ~ields are formed across a plurality of
electrode gaps. In the embodiment of the invention
illustrated in Figs. 1 through 4, the atmosphere in the
electrode gap 42 is maintained separate from the atmosphere in
the combustion chamber 60 to enable an electrostatic field to
be established at this electrode gap after a corona discharge
has been established at the electrode gap 44 which is exposed
to the atmosphere in the combustion chamber 60. The
relatively long duration of the extremely strong electrostatic
field at the electrode gap 42 enables a relatively large
number of fuel particles to be electrostatically attracted to
a portion of the combustion chamber 60 in which an ignition
spark is provided to thereby promote the ignition of a very
lean air-fuel mixture.
In the embodiment o~ the invention illustrated in Figs. S
through 8, a pair of electrostatic fields are established at a
pair of electrode gaps, one of the electrode gaps being formed
between the main electrode 140 and the secondary electrode 148
and the other electrode gap being formed between the secondary
.~ !
lV~391
,,
¦,el.ectrode 148 and the housing electrode 132. In this
~embodiment of the invention both of the electrode gaps are
exposed to the atmosphere in the combustion chamber. In order
to maximize the extent of the electrostatic fields, the
¦secondary electrode 148 is electrically insulated from the
¦main electrode 140 and the housing or tertiary electrode
surface 132. During the compression stroke of the enqine~ a
strong electrostatic field is established between the main
electrode 140 and the secondary electrode 148. Shortly
thereafter a strong electrostatic field is established between
the secondary electrode 148 and the housing electrode surface
132.
~I ~
